Conventionally, there is known an inline pressure sensor where a body and a sensor body are formed into one integral body, wherein a flow passage, through which a liquid such as a liquid medicine is made to flow, is formed in the body, and the sensor body detects a pressure of the liquid which is transmitted to a pressure receiving surface through a protective sheet (see Japanese Unexamined Patent Application, Publication No. 2005-207946 (hereinafter referred to as Patent Literature 1), for example).
The pressure sensor disclosed in Patent Literature 1 is configured to detect a pressure of a fluid which is transmitted to the sensor body through the protective sheet mounted on a lower surface of the sensor body.